Jenson Button was able to celebrate his world championship in Brazil on Sunday night, following an astonishing gesture of generosity by his defeated rival and friend Rubens Barrichello.

Jenson Button was able to celebrate his world championship in Brazil on Sunday night, following an astonishing gesture of generosity by his defeated rival and friend Rubens Barrichello.

Sao Paulo local and Interlagos pole sitter Barrichello had hoped to take the title down to the wire in Abu Dhabi in two weeks, but instead must travel to the United Arab Emirates now battling to retain just second in the drivers' standings.

Button must be back in Europe early this week for a Virgin sponsor commitment, meaning a British Airways flight before he had a chance to celebrate his achievement on Sunday evening.

But when word reached the Brawn camp that Button and his father's flight was delayed, 37-year-old Barrichello was so magnanimous in defeat as to offer the use of his private jet for a flight on Monday morning.

"I'm truly pleased for Jenson as a friend and he is a great champion," said the Brazilian.

"It was a true fight and I fought really hard but he really won it in the first half of the season," Barrichello added.

With the title fight now over, Button revealed the true extent of the pressure he has been under in recent weeks, particularly after qualifying a lowly 14th with Barrichello on pole in Brazil.

"After qualifying I felt sick because of how tough it was," he told reporters, having travelled without his girlfriend Jessica to Brazil.

"Without Jessica here, I was all on my own -- I did actually ask the boys if they would come and stay in my room last night (Saturday) because I knew it was going to be a tough night's sleep," Button added.

Race winner Mark Webber on Sunday wished Button well not for a wild party, but simply a good night's sleep. "He's been incredibly nervous, no question about that," said the Australian.

"He's been absolutely bricking himself the last few weeks, so he can sleep better now."